Thread-controlling mechanism for sewing-machines



(No Model.)

J. E. BERTRAND. THREAD CONTROLLING MECHANISM FOR SEWING MACHINES.

N0. 452,159. Patented May 12,1891.

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I UNITED STATES PATENT Orrrcn.

JOSEPH ELI BERTRAND, OF BOSTON, ASSIGNOR OF ONE-HALF TO MELLEN "BRAY, OF NEVTON, MASSACHUSETTS.

THREAD-CONTROLLING MECHANISM FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 452,159, dated May 12, 1891.

Application filed February 14:, 1891. Serial liTo- 381,412. (No model.)

chines, of which the following, taken in connection with the accompanying drawings, is

- a specification.

My invention relates to thread-tension and let-off mechanisms for sewing-machines, and is an improvement upon the invention described in the Letters Patent No. 432,012, granted to me July 15,1890; and it consists in certain novel features of construction, arrangement, and combination of parts, which will be readily understood by reference to the description of the drawings, and to the claims to be hereinafter given and in which my invention is clearly pointed out.

Figure 1 of the drawings is a sectional elevation of so much of a sewing-machine as is necessary to illustrate my present invention. Fig. 2 is a plan of the same parts. Fig. 3 is a sectional elevation of a portion of the same parts, the cutting plane being on line 00 m on Fig. 1. Fig. 4 is an elevation of the tensionwh-eel, its supporting-stand, and the stoppawl, and showing the locking-pawl cut in transverse section; and Fig. 5 is a sectional elevation, the cutting-plane being on line y y 011 Fig. 4.

The sewing-machine to which my present improvement has been applied is substantially the same as that shown and described in the Letters Patent No. 432,011, granted to me July 15, 1890, to which reference may be made for information regarding parts not shown in the drawings, forming a part of this specification, in which-- 0 is the upper tie-girt of the machine, and C the forward extension of the same.

D is the cam-shaft.

J is a stand carrying the thread-guiding sheave j 76? is the thread-carrier, mounted on the lower end of the vertical rod 71;, upon which is secured the pinion 7a, to which an oscillating motion is imparted by the reciprocating rack-bar I" is the take-up lever, only a portion of which is shown, having adjustably secured to its movable end the slatted block 19 carrying the grooved sheave 19 Q is the locking-lever, carrying at its front end the locking-pawl g and g is the cam for vibrating said locking lever and paw], all constructed, arranged, and operating in the same manner as described in said Letters Patent No. 432,011, except as will be hereinafter mentioned.

The tension-wheel g has formed in its periphery a groove, the bottom of which is polygonal or composed of a series of flat sides meeting each other at angles, precisely as in the Letters Patent No. 432,012.

I11 the Patent No. 432,012 the tension-wheel q had formed thereon at one side of the threadreceiving groove the ratchet-wheel g with the teeth of which the pawl g engaged to lock said tension-wheel against rotation when the take-up lever P was drawing the loop into the work after the shuttle had passed through the same, and said wheel was prevented from revolving freely onits axis when not locked only by friction caused by the tension of a spring which tended to clamp said wheel between the head of its axial pin and supporting stand or ear, and the thread for forming the loop above the work was drawn out by the looper-finger against the friction caused by said spring, which caused more or less chafing of the thread according to the amount of friction applied. To obviate this tendency to vwear the thread I dispense with the spring-pressure on the tension-wheel, mount or form thereon a second ratchet-wheel a, having its teeth formed with their radial shoulders facing in the opposite direction to those of the ratchet-wheel (1 provide the stop- .pawl 17, which is pivoted to the ears 1), formed upon and projecting from the stand Z2 in which is set the stud 0, upon which the tension-wheel q is mounted. The pawl Z) is made to automatically engage the teeth of the ratchratchet-wheel Ct at the proper time to rotate ICQ the tension-wheel 1 in the opposite direction to that indicated by the arrow 2 for the purpose of delivering the desired length of thread to form the next loop. The pawl c is secured upon a short shaft 0, mounted in a bearing in the arm f, depending from the lever Q, said shaft having secured upon its opposite end the lever 6 to the free end of which is connected one end of the spiral spring 9, the opposite end of which is connected to a pin or hook set in the lever Q, as shown in Figs. 1, 2, and A stand A is bolted to the tie-girt O in such a position that its upper end overhangs the lever Q in front of its pivotal axis, and has set therein the adjustable stop-screw h to limit the upward movement of the front arm of said lever Q, and consequent y of the pawl 6 whereby the length of thread delivered for each loop may be regulated according to the thickness of the stock being sewed, the rear end of the lever Q being moved toward the cam by the spring 0- as described in the before-cited patents.

A stand it is secured to and depends from the tie-girt O, and carries at its lower end the thread-guiding sheave 1', as shown in Figs. 1, 2, and 3. The needle-thread indicated by the dotted lines t passes from the spool or bobbin (not shown) to, under, and partially around the sheave 1', over and one or more times around the tension-wheel q, thence over the sheave p carried by the take-u p lever P, then down around the front side of the sheave through an eye in the thread-carrier 7c, and thence to the work. (Not shown.)

The operation of my invention is as follows: The parts being in the positions shown in the drawings, the tension-wheel being locked by the engagement of the pawl q with the ratchet-wheel (1 and the take-up lever P being at the extreme of its upward movement, having just completed the drawing up of the loop through which the shuttle has previously passed, as the shaft D continues to revolve in the direction indicated by the arrow 3 the throw 4 of the cam q passes from beneath the truck carried by the rear end of the lever Q, which is moved downward by the spring 7 thus raising the front arm of said lever and the locking-pawl so as to disengage said pawl from the ratchet-wheel (1 and at the same time moving the pawl e upward into e11- gagement with the teeth of the ratchet-wheel a, and moving said wheel about its axis in the direction opposite to that indicated by the arrow 2, this motion continuing untilthc truck at the rear end of the lever Q. comes in contact with the smaller portion of the cam (f, or the front arm of the lever Q comes in contact with the stop-screw 71, thus dcliveringthe requisite length of thread to form the next loop, the tension-wheclq being locked against backward movement by the stop -pawl Z).

i \Vhen the cam g has revolved until the throw 5 comes in contact with the truck 1', the pawl q is again brought into engagement with the ratchet-wheel g to lock said wheel. The pawl c is moved downward until disengaged from the teeth of the ratchet-wheel a by the nose of the stop-pawl Z), and then the take-up lever P is moved upward again to draw up another loop.

I claim- 1. In combination with a thread-tension wheel having a thread-receiving groove, the bottom of which is polygonal or composed of a series of fiat sides meeting each other at angles, two ratchet-wheels formed thereon or secured thereto, the radial shoulders of the teeth of which face in opposite directions, a pivoted lever, a cam for vibrating said lever, and two pawls carried by said lever, one of which is arranged to engage one of said ratchet-wheels to lock said tension-wheel and the other arranged to engage the teeth of the other ratchet wheel to move said tensionwheel about its axis, substantially as and for the purposes described.

2. The combination of the tension-wheel q, having a polygonal section between its flanges, the ratchet-wheels a and (1 connected to said wheel, the lever Q, the cam (1 the spring T the pawl to engage the ratchet g and the pawl c to engage the ratchet a, both carried by the lever Q, and the stop-pawl b to engage the ratchet a, all constructed and arranged to operate substantially as described.

The combinationot the tension-wheelq, having a polygonal section between its flanges, the two ratchet-wheels a and having teeth facingin opposite directions and formed upon or secured to said tension-wheel, the lever Q, the cam (f, the spring T the pawls q and 0, carried by said lever Q and constructed and arranged to engage the former with the ratchet and the latter with the ratchet a, the adjustable screw-stop h, and the stop-pawl b, constructed and arranged to engage the ratchet a and to serve as a shield to disengage the pawl c from the teeth of the wheel a, substantially as described.

In testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, on this 12th day of February, A. D. 1891.

JOSEPH ELl BERTRANI).

i'itnesses;

N. C. LonBARD, WALTER E. Loncitnn. 

